Update comments

protobuf/model_config.proto

@@ -1894,7 +1894,7 @@ message ModelMetrics
       //@@  .. cpp:var:: string family
       //@@
       //@@     The name of the metric family to override with the custom value.
-      //@@     Check the list of supported metric families
+      //@@     All core histogram metrics reported by Triton are customizable.
       //@@
       // https://github.com/triton-inference-server/server/blob/main/docs/user_guide/metrics.md#histograms
       //@@
@@ -1910,7 +1910,8 @@ message ModelMetrics
       //@@  .. cpp:var:: double buckets (repeated)
       //@@
       //@@     Repeated double type in ascending order for histogram bucket
-      //@@     boundaries. For example: [ -5.0, -2, 0, 3.5, 5 ].
+      //@@     boundaries. Each value represents a bucket range less than or
+      //@@     equal to itself. For example, [ -5.0, -2, 0, 3.5, 5 ].
       //@@
       repeated double buckets = 1;
     }